Bob, you may sound like a broken record, but at least it's stuck on a
particularly delightful song that I think everyone should listen to.
If everyone on this list had this book we'd see a 50% reduction in traffic
overnight :-)
Cheers
Jon
-----Original Message-----
From: Bob Hall [mailto:[EMAIL PROTECTED]]
Sent: 13 February 2001 11:13
To: [EMAIL PROTECTED]
Subject: Re: nested sets vs. key path method
>Hello,
>at the time I try to figure out what's the best way
>to get a kind of parent/child - hierarchy with unlimited
>subchild.
>My special attention is situated on really fast SELECT statements.
>
>Actually I'm using nested sets like:
>
>CREATE TABLE Personnel
>(emp CHAR(10) PRIMARY KEY,
>salary DECIMAL(6,2) NOT NULL,
>left INTEGER NOT NULL,
>right INTEGER NOT NULL);
>
>so I fetch all the bosses of an employee with this kind of SELECT:
>
>SELECT :myworker, B1.emp, (right - left) AS height
>FROM Personnel AS B1, Personnel AS E1
>WHERE E1.left BETWEEN B1.left AND B1.right
>AND E1.right BETWEEN B1.left AND B1.right
>AND E1.emp = :myworker;
>
>
>but now I wonder if it wouldn't be better to use the
>so called "key path method" where you put the whole
>top hierarchy info of a node into one column like:
>root/parent1/parent23/parent40/... and so on.
>
>Did someone make experience with one of this methods?
>
>thanx
>chris
At risk of sounding like a broken record:
'SQL For Smarties' by Joe Celko, chapters 28 & 29.
Bob Hall
Know thyself? Absurd direction!
Bubbles bear no introspection. -Khushhal Khan Khatak
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